From the Player's Guide under the HD help menu:
One more thing to cover before moving on is recruits that are listed as ineligible.
- In DIII, this means nothing, as DIII recruits need only to have a 2.0 GPA to be eligible.
- In DII, this means that the player will sit out his first year as a non-qualifier. He will be listed on your roster, and take up a scholarship, but he will not be allowed to practice with the team. After this season, the recruit will have 4 years of eligibility remaining.
- The situation is the same in DI, with one exception. The player will receive his 4th year of eligibility only if he has achieved a 2.7 cumulative GPA going into his 4th eligible year.
So 2.7 for D1, and they will always 4 years of eligibility for D2.